KR102469222B1 - Bonding material, manufacturing method of bonding material and bonding body - Google Patents

Abstract

In the joined body 10 in which the conductor 12 and the substrate 14 are joined by the bonding material 13, the bonding material 13 includes a sintered body in which silver powder is sintered, and the porosity of the sintered body is 8 to 8. It is 30%, and the surface roughness (Ra) of 500 nm or more and 3.3 micrometers or less of a joint surface is employ|adopted.

Description

Bonding material, manufacturing method of bonding material and bonding body

The present invention relates to a bonding material, a manufacturing method of the bonding material, and a bonded body. This application claims priority based on Japanese Patent Application No. 2019-188913 for which it applied to Japan on October 15, 2019, and uses the content here.

Power semiconductors using silicon carbide (SiC) are smaller than conventional semiconductors using silicon, have reduced energy loss, and are capable of operating even at high temperatures of 300°C or higher.

In the case of operating SiC power semiconductors at high temperatures, conventional solder having a heat resistance temperature of about 150 DEG C in an operating environment is not suitable as a bonding material. As a bonding material instead of this, the use of a paste in which metal fine particles are dispersed in a solvent (metal fine particle paste) having excellent heat resistance and electrical conductivity has been studied.

However, when a substrate and a chip are bonded at a high temperature using the above-mentioned metal fine particle paste, the solvent volatilizes during bonding and large pores (voids) are formed at the bonded portion, and the position of the chip is displaced in the resulting bonded body. There was a problem.

On the other hand, in order to suppress the formation of large pores in the joint portion, a method has been proposed in which silver particles are molded while being pressed to produce a bonding material, and the bonding material is used to bond between substrates (see Patent Document 1). .

Patent Document 1: Japanese Patent No. 4876979

However, when a substrate and a chip are bonded at a high temperature using the bonding material described in Patent Literature 1, there is a problem that the bonding strength of the obtained bonded body is not sufficient.

Here, an object of the present invention is to provide a bonding material capable of producing a bonded body having superior bonding strength than before, a manufacturing method of the bonding material, and a bonded body using the bonding material.

In order to solve the above problems, the present invention adopts the following configuration.

That is, the first aspect of the present invention includes a sintered body in which silver powder is sintered, the porosity of the sintered body is 8 to 30%, and the surface roughness (Ra) of the bonding surface is 500 nm or more and 3.3 It is a bonding material characterized in that it is less than μm.

A second aspect of the present invention is a method for producing a bonding material, comprising a step of obtaining a sintered body by heating a coating film formed using a dispersion of a solvent and silver powder, wherein the content of the solvent in the dispersion is 5 mass % or more and 25 mass% or less, characterized in that, a manufacturing method of a bonding material.

Further, a third aspect of the present invention, as a method for producing a bonding material, includes a step of obtaining a sintered body by heating a coated film formed using a solvent and a dispersion of silver powder, wherein the silver powder has a different average particle diameter ( The first silver particle group and the second silver particle group are mutually exclusive, the average particle diameter of the first silver particle group is 50 nm or more and less than 1000 nm, and the average particle of the second silver particle group A method for producing a bonding material characterized in that the diameter is 1 μm or more and less than 20 μm.

In the method for producing a bonding material according to the third aspect, the silver powder preferably further includes a third group of silver particles having an average particle diameter of 20 μm or more and less than 60 μm.

In the method for manufacturing a bonding material according to the second or third aspect, in the step of obtaining the sintered body, the coated film is preferably heated while the pressure applied to the coated film is 5 MPa or less.

In addition, the manufacturing method of the bonding material according to the second or third aspect further includes a step of polishing the surface of the sintered body, or a surface of the sintered body selected from the group consisting of silver, copper, tin, gold, and nickel It is preferable to have a step of coating one or more types of plating to be.

Further, a fourth aspect of the present invention is a bonded body characterized in that the conductor and the substrate are bonded by the bonding material according to the first aspect.

According to the present invention, it is possible to provide a bonding material capable of producing a bonded body having superior bonding strength than before, a manufacturing method of the bonding material, and a bonded body using the bonding material.

[Fig. 1] A cross-sectional view showing one embodiment of a bonded body according to the present invention.
[ Fig. 2A ] It is a microscopic image of a cross section of a bonding material by a scanning electron microscope.
[FIG. 2B] A microscopic image of a cross section of a bonding material by a scanning electron microscope.
[ Fig. 2c ] A microscopic image of a cross section of a bonding material by a scanning electron microscope.
[ Fig. 2d ] A microscopic image of a cross section of a bonding material by means of a scanning electron microscope.
[ Fig. 2e ] A microscopic image of a cross section of a bonding material by means of a scanning electron microscope.
[Fig. 3a] A microscopic image of the vicinity of a junction between a bonding material according to the present invention and a silver-plated copper plate.
[Fig. 3b] is a graph showing the relationship between the shear strength of the bonded body according to the present invention and the temperature and pressure during sintering.
[Fig. 4a] A microscopic image of the vicinity of the junction between the bonding material according to the present invention and the unplated copper plate.
[Fig. 4b] is a graph showing the relationship between the shear strength of the bonded body according to the present invention and the temperature and pressure during sintering.

1 is a cross-sectional view showing one embodiment of a bonded body according to the present invention.

A bonded body 10 shown in FIG. 1 is a laminated body in which a conductor 12 and a substrate 14 are bonded together by a bonding material 13 .

The bonded body 10 of this embodiment is characterized by the bonding material 13, and various well-known bonded bodies can be appropriately applied to other configurations.

[binder]

The bonding material of the present embodiment includes a sintered body in which silver powder is sintered, the porosity of the sintered body is 8 to 30%, and the surface roughness (Ra) of the bonding surface is 500 nm or more and 3.3 μm or less.

In this specification, a bonding material includes a bonding material between two objects, and typically includes a bonding material interposed between a conductor and a substrate to bond them together.

The porosity of the sintered body included in the bonding material of the present embodiment is 8 to 30%, preferably 8 to 20%, more preferably 9 to 15%.

When the porosity of the sintered body is within the above range, for example, the bonding strength between the conductor and the substrate (shear strength of the bonding body) can be improved.

Here, shear strength means what was measured by the method based on JIS　Z　3198-7:2003. A specific measurement method will be described later in the Examples.

In this specification, the porosity of the sintered body is measured as follows.

First, the sintered body is immersed in water, the volume of the sintered body is measured, and the mass of the sintered body is also measured. Further, the volume in case the sintered body corresponding to the mass does not have pores is calculated based on the theoretical density. The porosity of the sintered body is calculated from the measured volume and the theoretical volume in the case of not having pores.

As a method of controlling the porosity of the sintered body included in the bonding material of the present embodiment within the above range, for example, a method of appropriately selecting the type or particle diameter of silver powder, a method of appropriately setting pressure conditions during sintering, silver powder When producing a bonding material using a dispersion of , a method of adjusting the amount of solvent in the dispersion may be used.

The bonding material of the present embodiment may contain substances other than the sintered body formed from silver powder as long as the shear strength of the bonded body is sufficient.

It does not specifically limit as a shape of the bonding material of this embodiment, For example, flat plate shape, such as a disc shape and a rectangular plate; Cylindrical shape, columnar shape, polygonal shape, rod shape, such as polygonal columnar shape, spherical shape, etc. are mentioned.

In addition, the bonding material of this embodiment may have a thick portion of 1 mm or less in order to facilitate bonding.

The size of the bonding material is not particularly limited, and may be appropriately adjusted according to the specifications of the substrate and conductor. When the shape of the bonding material is disc-shaped, the diameter of the disc is preferably 0.5 to 50 mm, and more preferably 2 to 30 mm. When the shape of the bonding material is a rectangular plate, the long side length is preferably 0.5 to 50 mm, and more preferably 2 to 30 mm.

The surface roughness (Ra) of the bonding surface in the bonding material of the present embodiment is 500 nm or more, preferably 800 nm or more, more preferably 1.06 μm or more, still more preferably 1.4 μm or more.

In addition, the surface roughness (Ra) of the bonding surface in the bonding material of the present embodiment is 3.3 μm or less, preferably 3.1 μm or less, more preferably 2.9 μm or less, still more preferably 2.8 μm or less.

You may arbitrarily combine the upper limit value and the lower limit value of the surface roughness (Ra) of the bonding surface in the bonding material of this embodiment.

The combination of the upper limit and the lower limit of the surface roughness (Ra) is 500 nm or more and 3.3 μm or less, preferably 800 nm or more and 3.3 μm or less, more preferably 1.06 μm or more and 3.3 μm or less, still more preferably 1.4 μm. More than 2.8 μm or less.

As will be described later in Examples, when the surface roughness (Ra) of the bonding surface is within the above range, the shear strength of the bonded body can be made excellent.

In the bonding material of the present embodiment, the numerical ranges of the porosity of the sintered body and the surface roughness (Ra) of the bonding surface defined above may be combined arbitrarily.

The combination of the porosity of the sintered body and the surface roughness (Ra) of the bonding surface is a porosity of 8 to 30%, and a surface roughness (Ra) of 500 nm or more and 3.3 μm or less, preferably a porosity of 8 to 30% Further, the surface roughness (Ra) is 1.06 μm or more and 3.3 μm or less, more preferably the porosity is 8 to 27%, and the surface roughness (Ra) is 1.06 μm or more and 2.8 μm or less, still more preferably the porosity is 8 to 27%, and the surface roughness (Ra) is 1.4 μm or more and 2.8 μm or less.

Surface roughness:

The surface roughness of the bonding surface of the bonding material can be measured as follows. Using a super-depth color 3D shape measuring microscope (Keyence, VK-9510), the surface roughness is measured for five arbitrary locations on the surface of the bonding material, and an average value is calculated.

The method of controlling the surface roughness (Ra) of the bonding surface of the bonding material within the above range is not particularly limited, and examples thereof include a method of polishing the surface of the sintered body and a method of plating the surface of the sintered body. Although it does not specifically limit as a type of plating, Plating of 1 type of metal selected from the group which consists of silver, copper, tin, gold, and nickel, or an alloy consisting of 2 or more types is mentioned. The plating may be obtained by overlapping two or more layers of plating having different compositions.

When the bonding material of the present embodiment has a polished surface of a sintered body, the surface roughness (Ra) of the bonding surface in the bonding material is 500 nm or more, preferably 1.06 μm or more, and more preferably 1.5 μm. or more, more preferably 1.7 μm or more.

When the bonding material of the present embodiment has a polished surface of a sintered body, the surface roughness (Ra) of the bonding surface in the bonding material is 3.3 µm or less, preferably 3.1 µm or less, and more preferably 2.9 µm. or less, more preferably 2.8 μm or less.

You may combine the upper limit value and the lower limit value of the surface roughness (Ra) of the bonding surface in a bonding material arbitrarily.

When the bonding material of the present embodiment has a polished surface of a sintered body, the combination of the upper limit and the lower limit of the surface roughness (Ra) of the bonding surface in the bonding material is 500 nm or more and 3.3 μm or less, preferably 1.06 μm. 3.3 μm or less, more preferably 1.5 μm or more and 2.9 μm or less, still more preferably 1.7 μm or more and 2.8 μm or less.

In the bonding material of the present embodiment, when the surface of the sintered body is polished, the numerical ranges of the porosity of the sintered body and the surface roughness (Ra) of the bonding surface defined above may be arbitrarily combined.

When the bonding material of the present embodiment has a polished surface of a sintered body, the combination of the porosity of the sintered body and the surface roughness (Ra) of the bonding surface is 8 to 30% in porosity, and the surface roughness (Ra) is 500%. nm or more and 3.3 μm or less, preferably the porosity is 8 to 30%, and the surface roughness (Ra) is 1.06 μm or more and 3.3 μm or less, more preferably the porosity is 8 to 27%, and the surface roughness (Ra) is 1.5 μm or more and 3.1 μm or less, more preferably, the porosity is 8 to 27%, and the surface roughness (Ra) is 1.7 μm or more and 2.8 μm or less.

When the bonding material of the present embodiment is obtained by plating the surface of a sintered body, the surface roughness (Ra) of the bonding surface in the bonding material is 500 nm or more, preferably 800 nm or more, and more preferably 1.06 It is μm or more, more preferably 1.4 μm or more. When the bonding material of the present embodiment is one obtained by plating the surface of a sintered body, the surface roughness (Ra) of the bonding surface in the bonding material is 3.3 µm or less, preferably 2.5 µm or less, and more preferably 2.0 µm or less. It is μm or less, more preferably 1.8 μm or less.

You may combine the upper limit value and the lower limit value of the surface roughness (Ra) of the bonding surface in a bonding material arbitrarily.

When the bonding material of the present embodiment is one in which the surface of the sintered body is plated, the combination of the upper limit and the lower limit of the surface roughness (Ra) of the bonding surface in the bonding material is 500 nm or more and 3.3 μm or less, preferably 1.06 It is not less than 3.3 μm, more preferably not less than 1.06 μm and not more than 2.0 μm, and still more preferably not less than 1.4 μm and not more than 1.8 μm.

In the bonding material of the present embodiment, when the surface of the sintered body is plated, the numerical ranges of the porosity of the sintered body and the surface roughness (Ra) of the joint surface defined above may be arbitrarily combined.

When the bonding material of the present embodiment is one in which the surface of the sintered body is plated, the combination of the porosity of the sintered body and the surface roughness (Ra) of the bonding surface is 8 to 30% in porosity, and the surface roughness (Ra) is 500 nm or more and 3.3 μm or less, preferably the porosity is 8 to 27%, and the surface roughness (Ra) is 1.06 μm or more and 3.3 μm or less, more preferably the porosity is 9 to 15%, and the surface The roughness (Ra) is 1.06 μm or more and 2.0 μm or less, more preferably the porosity is 9 to 13%, and the surface roughness (Ra) is 1.4 μm or more and 1.8 μm or less.

The bonding material of the present embodiment described above contains a sintered silver powder having a porosity of 8 to 30%, and has a surface roughness (Ra) of 500 nm or more and 3.3 µm or less of the bonding surface. In this way, since the surface roughness (Ra) of the bonding surface is in a specific range and the sintered body of silver powder having a specific porosity is employed, according to the bonding material of the present embodiment, a bonded body having superior bonding strength than before can be obtained. can be produced

Additionally, this sintered body does not melt even under a temperature higher than the melting point of the silver powder. In addition, by using a bonding material containing this sintered body, bonding can be performed at a temperature lower than the melting point of the bulk.

[Method of manufacturing bonding material]

The manufacturing method of the bonding material of this embodiment has the process of heating the coating film formed using the dispersion of a solvent and silver powder, and obtaining a sintered compact.

(solvent)

In the dispersion liquid of this embodiment, silver powder is dispersed in a solvent.

Examples of the solvent herein include water, alcohol solvents, glycol ether solvents, and terpineols.

Examples of the alcohol solvent include isopropyl alcohol, 1,2-butanediol, isobornyl cyclohexanol, 2,4-diethyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 2,5 -Dimethyl-2,5-hexanediol, 2,5-dimethyl-3-hexyne-2,5-diol, 2,3-dimethyl-2,3-butanediol, 1,1,1-tris(hydroxymethyl) Ethane, 2-ethyl-2-hydroxymethyl-1,3-propanediol, 2,2'-oxybis(methylene)bis(2-ethyl-1,3-propanediol), 2,2-bis(hydroxyl) Roxymethyl) -1,3-propanediol, 1,2,6-trihydroxyhexane, bis [2,2,2-tris (hydroxymethyl) ethyl] ether, 1-ethynyl-1-cyclohexanol , 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, erythritol, threitol, guayacol glycerol ether, 3,6-dimethyl-4-octyl-3,6-diol, 2,4, 7,9-tetramethyl-5-decyl-4,7-diol etc. are mentioned.

As the glycol ether solvent, diethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, 2-methylpentane-2,4-diol, diethylene glycol monohexyl ether, diethylene glycol dibutyl ether, triethylene glycol monobutyl ether; and the like.

(silver powder)

As the silver powder here, it is preferable to use a combination of silver particle groups having different average particle diameters. A bonding material having a specific porosity (8 to 30%) can be easily produced by using together those having different average particle diameters.

Average Particle Diameter:

The value of median diameter (D50) is employ|adopted as the average particle diameter of a group of silver particles. In the present invention, the median diameter (D50) of each silver powder means a value (volume average particle diameter) measured by a laser diffraction method using SALD-2300 (manufactured by Shimadzu Corporation).

As a suitable combination of silver particle groups with different average particle diameters, a combination of a silver particle group of nano order and a silver particle group of micro order is mentioned.

For example, including a first silver particle group and a second silver particle group having different average particle diameters, the average particle diameter of the first silver particle group is 50 nm or more and less than 1000 nm, and the second silver particle group It is preferable that the average particle diameter of a particle group is 1 micrometer or more and less than 20 micrometer.

The average particle diameter of the 1st silver particle group is 50 nm or more and less than 1000 nm, Preferably they are 100 nm or more and 800 nm or less, More preferably, they are 200 nm or more and 500 nm or less.

The average particle diameter of the second silver particle group is 1 μm or more and less than 20 μm, preferably 3 μm or more and 15 μm or less, more preferably 3 μm or more and 10 μm or less.

By using the first silver particle group and the second silver particle group together, a bonding material having a specific porosity (8 to 30%) can be easily produced, and a bonded body with increased bonding strength is easy to obtain.

Although the shape of the silver particle of the 1st silver particle group is not specifically limited, Either spherical shape or non-spherical shape may be sufficient. Examples of non-spherical shape include flake shape, needle shape, angle shape, dendrite shape, granular shape, irregular shape, stacked shape, plate shape, ultra-thin plate shape, hexagonal plate shape, columnar shape, rod shape, porous shape, fibrous shape, and lumpy shape.狀, spongy, squiggly, round, etc. may be mentioned. Among these shapes, a spherical shape and a columnar shape are preferable.

It is preferable that the 2nd silver particle group contains flaky silver particles. In this case, as for the 2nd silver particle group, the majority of silver particles should just be recognized as flake shape (flaky shape or flaky shape) under a microscope. Typically, it means that 51% by mass or more of the particles (primary particles) constituting the second silver particle group have a flake (flake or flake) shape. Here, the flake-shaped (flaky or flaky) particles mean particles having an aspect ratio (longest major axis/shortest minor axis ratio) of 5 to 300.

The silver powder of this embodiment may also contain the 3rd silver particle group whose average particle diameter is 20 micrometers or more and less than 60 micrometers further.

The average particle diameter of the third silver particle group is 20 μm or more and less than 60 μm, preferably 30 μm or more and 50 μm or less, more preferably 35 μm or more and 45 μm or less.

By using the third silver particle group in addition to the first silver particle group and the second silver particle group, a bonding material having a specific porosity (8 to 30%) can be produced more stably.

Although the shape of the silver particle of the 3rd silver particle group is not specifically limited, Either spherical shape or non-spherical shape may be sufficient. Examples of non-spherical shapes include flakes, needles, angular shapes, dendrites, granules, irregular shapes, stacked shapes, plates, ultrathin plates, hexagonal plates, columnar shapes, rods, porous shapes, fibrous shapes, lumpy shapes, spongy shapes, squarish shapes, round shapes, and the like. can Among these shapes, a spherical shape and a columnar shape are preferable.

In addition, the 1st silver particle group, the 2nd silver particle group, and the 3rd silver particle group may use 2 or more types from which average particle diameters differ as each silver particle group.

In the silver powder of this embodiment, it is preferable to use 2 or more types with different average particle diameters as a 2nd silver particle group. For example, as the second silver particle group, it is preferable to use a combination of a silver particle group having an average particle diameter of 1 µm or more and less than 10 µm and a silver particle group having an average particle diameter of 10 µm or more and less than 20 µm.

As the silver powder of the present embodiment, when silver particle groups having different average particle diameters are used in combination, the ratio of the first silver particle group is 1 to 50 with respect to the total mass (100% by mass) of the silver powder. It is preferable that it is mass %, 1-30 mass % is more preferable, and 3-10 mass % is still more preferable.

The ratio of the second silver particle group is preferably 30 to 99 mass%, more preferably 45 to 90 mass%, and 50 to 90 mass% with respect to the total mass (100 mass%) of the silver powder. more preferable

When the third silver particle group is further used in combination, the ratio of the third silver particle group is preferably 1 to 70 mass%, and 1 to 50 mass% with respect to the total mass (100 mass%) of the silver powder. Mass % is more preferable, and 1-45 mass % is still more preferable. However, the sum of the ratios of the 1st silver particle group, the 2nd silver particle group, and the 3rd silver particle group does not exceed 100 mass %.

(dispersion)

In the dispersion of the solvent and the silver powder in the present embodiment, the content of the solvent in the dispersion is preferably 5% by mass or more and 25% by mass or less, more preferably 5% by mass or more and 20% by mass or less , more preferably 5% by mass or more and 15% by mass or less, particularly preferably 6% by mass or more and 10% by mass or less.

By setting the content of the solvent in the dispersion to 5% by mass or more and 25% by mass or less, a sintered body having a porosity of 8 to 30% can be easily obtained.

When the dispersion is sintered, the solvent in the dispersion is volatilized and pores are formed in the sintered body. By setting the content of the solvent in the dispersion within the above range, the porosity of the sintered body can be made 8 to 30%.

Next, the manufacturing method of the bonding material of this embodiment is explained in detail.

Process for obtaining a sintered body:

In the step of obtaining a sintered body in this embodiment, a coated film formed using a solvent and a dispersion of silver powder is heated to obtain a sintered body.

First, the above dispersion liquid is coated on a substrate to form a coated film. Although it does not specifically limit as a method of coating, Dispensing coating, printing coating, spray coating, brushing, pouring, etc. are mentioned.

Examples of the base material include, but are not limited to, glass, quartz, silicon, and metal. As will be described later in the examples, as the metal, for example, brass can be used, but it is not limited thereto.

In the case of using a metal base, if a lubricating release agent is applied to the base in advance, the sintered body can be easily peeled off from the base.

Next, the coated film is heated to obtain a sintered body. The heating temperature can be appropriately set as long as it is a temperature at which a sintered body can be obtained. For example, 150°C or more and 300°C or less are preferable, and 200°C or more and 250°C or less are more preferable.

The time for heating the coated film can be appropriately set as long as the sintered body can be obtained. For example, 15 minutes or more and 180 minutes or less are preferable, and 30 minutes or more and 90 minutes or less are more preferable.

In the step of obtaining a sintered body in the present embodiment, it is possible to suppress the pressure applied to the coated film to preferably 5 MPa or less, and it is also possible to suppress it to 1 MPa or less. It is also possible.

Next, the obtained sintered body may be cut according to the specifications of the substrate and conductor. The tool used for cutting the sintered body is not particularly limited, and examples thereof include scissors, a diamond knife, and a paper cutter. In this specification, there are cases where the above-described cut sintered body is simply referred to as a sintered body.

As the manufacturing method of the bonding|jointing material demonstrated above, more specifically, the embodiment shown below is mentioned suitably.

Embodiment (i): A method for producing a bonding material comprising a step of obtaining a sintered body by heating a coated film formed using a dispersion of a solvent and silver powder, wherein the content of the solvent in the dispersion is 5% by mass or more and 25% by mass or less. .

According to Embodiment (i), a bonding material containing a sintered body having a porosity of 8 to 30% can be easily manufactured by adjusting the content of the solvent in the dispersion to a specific ratio.

Embodiment (ii): A coating film formed using a dispersion of a solvent and silver powder is heated to obtain a sintered body, the content of the solvent in the dispersion is 5% by mass or more and 25% by mass or less, and the silver powder silver, it consists of a first silver particle group and a second silver particle group having different average particle diameters, the average particle diameter of the first silver particle group is 50 nm or more and less than 1000 nm, and the second silver particle group A method for producing a bonding material wherein the average particle diameter of the particle group is 1 μm or more and less than 20 μm.

The ratio of the 1st silver particle group of the said silver powder is 1-50 mass %, and the ratio of the 2nd silver particle group may be 50-99 mass %, for example.

The ratio of the 1st silver particle group of the said silver powder is 5-30 mass %, and the ratio of the 2nd silver particle group may be 70-95 mass %, for example.

The ratio of the 1st silver particle group of the said silver powder is 5-15 mass %, and the ratio of the 2nd silver particle group may be 85-95 mass %, for example.

The ratio of the first silver particle group and the second silver particle group is a ratio with respect to the total mass (100% by mass) of the silver powder. Moreover, the sum of the ratio of the said 1st silver particle group and the 2nd silver particle group does not exceed 100 mass %.

According to Embodiment (ii), the bonding material containing the sintered compact of 8 to 30% of porosity can be easily manufactured by combining and using the silver particle group which has a specific average particle diameter.

Embodiment (iii): A coating film formed using a dispersion of a solvent and silver powder is heated to obtain a sintered body, wherein the content of the solvent in the dispersion is 5% by mass or more and 25% by mass or less, and the silver powder It consists of a first silver particle group, a second silver particle group, and a third silver particle group having different average particle diameters, and the average particle diameter of the first silver particle group is 50 nm or more and less than 1000 nm. wherein the average particle diameter of the second silver particle group is 1 μm or more and less than 20 μm, and the average particle diameter of the third silver particle group is 20 μm or more and less than 60 μm.

The above-mentioned silver powder has, for example, the ratio of the first silver particle group is 1 to 50% by mass, the ratio of the second silver particle group is 30 to 98% by mass, and the ratio of the third silver particle group is This 1-69 mass % may be sufficient.

The above-mentioned silver powder has, for example, the ratio of the first silver particle group is 1 to 30% by mass, the ratio of the second silver particle group is 30 to 90% by mass, and the ratio of the third silver particle group is This 5-60 mass % may be sufficient.

The above-mentioned silver powder has, for example, the ratio of the first silver particle group is 3 to 8% by mass, the ratio of the second silver particle group is 45 to 72% by mass, and the ratio of the third silver particle group is This 20-50 mass % may be sufficient.

The ratio of the above-mentioned 1st silver particle group, 2nd silver particle group, and 3rd silver particle group is a ratio with respect to the mass (100 mass %) of the total of silver powder. Moreover, the sum of the ratios of a 1st silver particle group, a 2nd silver particle group, and a 3rd silver particle group does not exceed 100 mass %.

According to Embodiment (iii), the bonding material containing the sintered compact of 8 to 30% of porosity can be easily manufactured by using combining the silver particle group which has a specific average particle diameter.

In addition to the process of obtaining a sintered compact, the manufacturing method of the bonding material of this embodiment may have processes other than this.

For example, in order to control the roughness of the surface of the obtained sintered body, a step of polishing the surface of the sintered body on the rear side of the process of obtaining the sintered body, or, from the group consisting of silver, copper, tin, gold and nickel on the surface of the sintered body You may further have the process of coating 1 or more types of plating selected.

When the manufacturing method of the bonding material of the present embodiment includes the step of polishing the surface of the sintered body or the step of applying the plating, the bonding surface of the bonding material obtained by the polishing step or the plating step. The surface roughness (Ra) of is 500 nm or more, preferably 800 nm or more, more preferably 1.06 μm or more, still more preferably 1.4 μm or more.

On the other hand, the upper limit of the surface roughness (Ra) of the joint surface in the bonding material obtained by the polishing step or the plating step is 3.3 μm or less, preferably 3.1 μm or less, more preferably 2.9 μm. or less, more preferably 2.8 μm or less.

The upper limit value and the lower limit value of the surface roughness (Ra) of the bonding surface in the bonding material obtained by the polishing process or the plating process may be arbitrarily combined.

The combination of the upper limit and the lower limit of the surface roughness (Ra) of the joint surface in the bonding material obtained by the polishing step or the plating step is 500 nm or more and 3.3 μm or less, preferably 800 nm or more and 3.3 μm. or less, more preferably 1.06 μm or more and 3.3 μm or less, still more preferably 1.4 μm or more and 2.8 μm or less.

Process of polishing the surface of the sintered body:

The method for polishing the surface of the sintered body is not particularly limited, and examples thereof include chemical polishing, electrolytic polishing, and mechanical polishing. As will be described later in the examples, by polishing the surface of the sintered body using abrasive paper of No. 2000, a bonding material capable of producing a bonded body having sufficient bonding strength can be obtained.

When the manufacturing method of the bonding material of the present embodiment has the step of polishing the surface of the sintered body described above, the surface roughness (Ra) of the bonding surface of the bonding material obtained by the polishing step is 500 nm or more, It is preferably 1.06 μm or more, more preferably 1.5 μm or more, and even more preferably 1.7 μm or more.

On the other hand, the surface roughness (Ra) of the bonding surface in the bonding material obtained by the polishing step is 3.3 μm or less, preferably 3.1 μm or less, more preferably 2.9 μm or less, still more preferably It is 2.8 μm or less.

You may combine the upper limit value and the lower limit value of the surface roughness (Ra) of the joint surface in a bonding material obtained by the polishing process arbitrarily.

The combination of the upper limit and the lower limit of the surface roughness (Ra) of the joint surface in the bonding material obtained by the polishing step is 500 nm or more and 3.3 μm or less, preferably 1.06 μm or more and 3.3 μm or less, more preferably It is preferably 1.5 μm or more and 2.9 μm or less, more preferably 1.7 μm or more and 2.8 μm or less.

Process of coating the surface of the sintered body with plating:

The method of plating the surface of the sintered body is not particularly limited, and examples thereof include electroplating, electroless plating, and vacuum plating. The type of plating is not particularly limited, but examples include plating of one type of metal selected from the group consisting of silver, copper, tin, gold, and nickel, or an alloy composed of two or more types. The plating step may be performed by layering two or more layers of plating having different compositions.

For example, when one of the objects to be bonded is a copper substrate, the surface of the sintered body may be coated with copper plating. As a result, the affinity between the bonding material and the copper substrate is strengthened, and bonding strength is easily increased.

When the manufacturing method of the bonding material of the present embodiment includes the step of coating the surface of the sintered body with plating, the surface roughness (Ra) of the bonding surface in the bonding material obtained by the plating process is 500 nm or more. , preferably 800 nm or more, more preferably 1.06 μm or more, still more preferably 1.4 μm or more.

On the other hand, the surface roughness (Ra) of the bonding surface of the bonding material obtained by the plating step is 3.3 μm or less, preferably 2.5 μm or less, more preferably 2.0 μm or less, still more preferably is 1.8 μm or less.

The upper limit value and the lower limit value of the surface roughness (Ra) of the bonding surface in the bonding material obtained by the plating step may be arbitrarily combined.

The surface roughness of the joint surface of the bonding material obtained by the plating step is 500 nm or more and 3.3 μm or less, preferably 1.06 μm or more and 3.3 μm or less, more preferably 1.06 μm or more and 2.0 μm or less. and more preferably 1.4 μm or more and 1.8 μm or less.

When the manufacturing method of the bonding material has a process of polishing the surface of the sintered body or a process of applying the plating to the rear side of the step of obtaining the sintered body in embodiment (i), the bonding material obtained is The surface roughness (Ra) of is in a specific range, and the sintered body has a specific porosity.

When the manufacturing method of the bonding material has the process of polishing the surface of the sintered body or the process of applying the plating to the rear side of the step of obtaining the sintered body in embodiment (ii), the bonding material obtained is the bonding surface The surface roughness (Ra) of is in a specific range, and the sintered body of the silver powder having a specific porosity is obtained.

When the manufacturing method of the bonding material has the process of polishing the surface of the sintered body or the process of applying the plating to the rear end side of the step of obtaining the sintered body, the bonding material obtained is the joint surface The surface roughness (Ra) of is in a specific range, and the sintered body of the silver powder having a specific porosity is obtained.

[conjugate]

As shown in Fig. 1, in the bonded body of the present embodiment, a conductor and a substrate are bonded by the bonding material described above.

As the conductor, chip components such as capacitors and resistors, Si chips, SiC chips, GaN, and the like obtained by forming semiconductor elements such as resistors, transistors, capacitors, and integrated circuits on a wafer, and then cutting out sections of each semiconductor element from the wafer, can be used. can be heard

Examples of the substrate include a circuit board, a glass fiber reinforced epoxy printed circuit board, a polyimide substrate, a ceramic substrate, a metal substrate, and a Cu lead frame.

As temperature at the time of joining, 150 degreeC or more and 400 degrees C or less are preferable, for example, 200 degrees C or more and 300 degrees C or less are more preferable.

As a method of bonding the conductor and the substrate using the bonding material described above, a known method can be employed.

Although it does not specifically limit as a pressure at the time of joining, For example, 0.1 MPa or more and 3 MPa or less may be sufficient.

The atmosphere at the time of joining may be in air or in nitrogen.

In the bonded body of the present embodiment described above, a bonding material containing a sintered silver powder having a porosity of 8 to 30% and having a surface roughness (Ra) of 500 nm or more and 3.3 μm or less of the bonding surface is applied. For this reason, such a bonded body has superior bonding strength than before.

Example

Hereinafter, the present invention will be described by examples, but the present invention is not limited to the following examples.

<Ingredients Used>

As silver powder, the silver particle group shown below was used.

Silver particle group 1A: average particle diameter = 300 nm

Silver particle group 2A: Average particle diameter = 4 μm

Silver particle group 2B: Average particle diameter = 10 μm

Silver particle group 3: average particle diameter = 42 μm

Silver particle group 1B: average particle diameter = 50 nm

The shape of the silver particle of silver particle group 1A, 1B, 2A, and 3 was spherical, and the shape of the silver particle of silver particle group 2B was flake shape.

As a solvent, ethylene glycol was used.

As the average particle diameter described above, the value of the median diameter (D50) was adopted. In the present invention, the median diameter (D50) of each silver powder means (volume average diameter) measured by a laser diffraction method using SALD-2300 (manufactured by Shimadzu Corporation).

<Preparation of Silver Powder Dispersion>

The above-mentioned silver particle group and solvent were mixed with the composition shown in Table 1, and dispersion liquids 1-9 were prepared. In Table 1, each value of a silver particle group shows the ratio (mass %) of the mass of each silver particle group with respect to the total mass of silver powder. In addition, the ratio of the solvent represents the ratio (mass %) of the mass of the solvent to the total mass of the silver powder and the solvent.

<Manufacture of bonding material>

(Example 1)

Using the dispersion liquid 1, a coating film was produced on a base of brass.

As brass, what consists of 65 mass % of copper and 35 mass % of zinc was used.

Process for obtaining a sintered body:

The produced coated film was heated at 200°C for 30 minutes without pressure to obtain a sintered body. Using scissors, the obtained sintered body was cut into small pieces (length Х width dimension: 3 mm Х 3 mm).

Polishing process:

The surface of the sintered body of the obtained small pieces was polished using abrasive paper No. 2000 (a water-resistant abrasive paper sheet manufactured by Sankyo Rikagaku) to obtain a bonding material.

(Example 2)

A bonding material was obtained in the same manner as in Example 1, except that the sintering conditions were changed to 250°C for 30 minutes.

(Example 3)

Using the dispersion 1, a coating film was produced on the base of the brass described above.

Process for obtaining a sintered body:

The produced coated film was heated at 200°C for 30 minutes without pressure to obtain a sintered body.

Silver plating process:

The obtained sintered body was immersed in a solution in which silver acetoacetate was dissolved in 2-ethylhexylamine, and left still at 40°C for 10 minutes. Then, the sintered body was taken out of the liquid mixture and dried.

(Example 4)

A bonding material was obtained in the same manner as in Example 3 except that the sintering conditions were changed to 250°C for 30 minutes.

(Example 5)

A bonding material was obtained in the same manner as in Example 1 except that the dispersion liquid used was changed to dispersion liquid 2.

(Example 6)

A bonding material was obtained in the same manner as in Example 5, except that the sintering conditions were changed to 250°C for 30 minutes.

(Example 7)

A bonding material was obtained in the same manner as in Example 3 except that the dispersion liquid used was changed to the dispersion liquid 2.

(Example 8)

A bonding material was obtained in the same manner as in Example 7, except that the sintering conditions were changed to 250°C for 30 minutes.

(Example 9)

A bonding material was obtained in the same manner as in Example 2 except that the dispersion liquid used was changed to dispersion liquid 3.

(Example 10)

A bonding material was obtained in the same manner as in Example 2 except that the dispersion liquid used was changed to dispersion liquid 4.

(Example 11)

A bonding material was obtained in the same manner as in Example 5, except that the sintering conditions were changed to 90 minutes at 250°C.

(Example 12)

A bonding material was obtained in the same manner as in Example 2 except that the dispersion liquid used was changed to dispersion liquid 5.

(Example 13)

A bonding material was obtained in the same manner as in Example 2 except that the dispersion liquid used was changed to dispersion liquid 6.

(Example 14)

Using dispersion 2, a coating film was produced on the base of the brass described above.

Process for obtaining a sintered body:

The produced coated film was heated at 250°C for 30 minutes without pressure to obtain a sintered body.

Copper plating process:

The obtained sintered body was immersed in a solution in which copper (II) formate tetrahydrate (manufactured by Wako Pure Chemical Industries, Ltd., product number: LKJ3210, primary average particle diameter: 20 μm) was dissolved in 2-ethylhexylamine in a nitrogen atmosphere. and left still at 140°C for 10 minutes. Then, the sintered body was taken out of the liquid mixture and dried.

(Comparative Example 1)

A bonding material was obtained in the same manner as in Example 1 except that the dispersion liquid used was changed to dispersion liquid 7.

(Comparative Example 2)

A bonding material was obtained in the same manner as in Comparative Example 1, except that the sintering conditions were changed to 30 minutes at 250°C and sintered while pressurizing at 0.4 MPa during sintering.

(Comparative Example 3)

A bonding material was obtained in the same manner as in Comparative Example 1 except that sintering was performed while pressing at 0.4 MPa during sintering.

(Comparative Example 4)

A bonding material was obtained in the same manner as in Comparative Example 1 except that the sintering conditions were changed to 250°C for 30 minutes.

(Comparative Example 5)

A bonding material was obtained in the same manner as in Example 1 except that the dispersion liquid used was changed to dispersion liquid 7 and the surface of the sintered body was not polished.

(Comparative Example 6)

A bonding material was obtained in the same manner as in Comparative Example 5, except that the sintering conditions were changed to 250°C for 30 minutes.

(Comparative Example 7)

A bonding material was obtained in the same manner as in Example 2, except that the dispersion liquid used was changed to dispersion liquid 8 and the surface of the sintered body was not polished.

(Comparative Example 8)

A bonding material was obtained in the same manner as in Example 2 except that the dispersion liquid used was changed to dispersion liquid 8.

(Comparative Example 9)

A bonding material was obtained in the same manner as in Example 2 except that the dispersion liquid used was changed to dispersion liquid 9 and the surface of the sintered body was not polished.

(Comparative Example 10)

A bonding material was obtained in the same manner as in Example 2 except that the dispersion liquid used was changed to dispersion liquid 9.

For each bonding material obtained in Examples 1 to 14 and Comparative Examples 1 to 10, the porosity and surface roughness were respectively measured by the measuring method shown below.

[Measurement of Porosity]

The bonding material was immersed in water, the volume of the bonding material was measured, and the mass of the bonding material was measured. In addition, the volume in the case where the bonding material corresponding to the mass does not have pores was calculated based on the theoretical density. The porosity was calculated from the measured volume and the theoretical volume in the case of no porosity.

[Measurement of surface roughness]

Using a super-depth color 3D shape measuring microscope (Keyence, VK-9510), surface roughness was measured for five arbitrary locations on the surface of the bonding material, and an average value was calculated. The size of the measurement location was 1400 µmХ1050 µm.

Table 2 shows the sintering conditions, porosity, and surface roughness of each bonding material obtained in Examples 1 to 14 and Comparative Examples 1 to 10.

When the silver powder contains silver particle group 1 and silver particle group 2, and the content of the solvent in the dispersion is 5% by mass or more and 25% by mass or less, the porosity of the sintered bodies of the bonding materials obtained in Examples 1 to 14 is 8 to 30% was

After embedding the obtained sintered compact with resin, the sintered compact embedded with resin was cut|disconnected using the ion milling apparatus IM4000PLUS (made by Hitachi High-Technology Co., Ltd., Kabushiki Kaisha), and the smoothed slice was obtained. The obtained slice was observed using a scanning electron microscope (SEM). A microscopic image by SEM of the cross section of the bonding material is shown in FIG. 2 .

2A is a microscopic image by SEM of the cross section of the bonding material of Example 2. 2B is a microscope image by SEM of the cross section of the bonding material of Example 6. 2C is a microscopic image by SEM of the cross section of the bonding material of Comparative Example 4. 2D is a microscope image by SEM of the cross section of the bonding material of Example 9. 2E is a microscopic image by SEM of the cross section of the bonding material of Example 10.

As a result, many pores were recognized in the cross section of the bonding material of Examples 2, 6, 9, and 10 compared to the cross section of the bonding material of Comparative Example 4.

<Preparation of conjugate>

(Examples 21 to 34, Comparative Examples 11 to 20)

As a conductor, a Si chip (vertical Х horizontal dimensions: 3 mm Х 3 mm) in which a Ti layer (thickness of 40 nm) and an Ag layer (thickness of 1000 nm) were laminated by sputtering in order from the Si chip side was used. As the bonding material, each bonding material of Examples 1 to 14 and Comparative Examples 1 to 10 was used. The thickness of each bonding material was 100 μm. As a substrate, a copper substrate was used.

After stacking the substrate, bonding material, and conductor in this order so that the polished surface of the bonding material becomes the bonding surface, they are bonded by heating in the air at a temperature of 250° C. under a pressure of 0.4 MPa to form a bonded body. Got it. Bonded bodies of Examples 21 to 34 and Comparative Examples 11 to 20 were obtained using the respective bonding materials of Examples 1 to 14 and Comparative Examples 1 to 10.

The shear strength of the obtained bonded bodies of Examples 21 to 34 and Comparative Examples 11 to 20 was measured according to the measurement method shown below. The results are shown in Table 3.

[Sheer strength test]

The shear strength (shear strength) of each bonded body of Examples 21 to 34 and Comparative Examples 11 to 20 was measured as follows. Table 3 shows the measurement results.

Shear strength test:

For each bonded body obtained, a universal bond tester "Nordson DAGE" Series 4000 (manufactured by Nordson Corporation) was used, under room temperature (25 ° C.) conditions, by a method in accordance with JIS "Z" 3198-7: 2003, between the Si chip and the substrate. Measurements of the shear strength (MPa) of were performed. Measurements were performed 5 times for each sample, and the average value of shear strength (MPa) was calculated.

When the bonding materials of Examples 1 to 14 having a porosity of 8 to 30% were used, the shear strength of the bonded bodies of Examples 21 to 34 was sufficient.

When the bonding materials of Examples 1 to 14 having a surface roughness (Ra) of 500 nm or more and 3.3 μm or less of the bonded surfaces were used, the shear strength of the obtained bonded bodies of Examples 21 to 34 was sufficient.

When the bonding materials of Examples 1, 2, 5, 6, and 9 to 13 obtained by polishing the surface of the sintered body were used, the obtained bonded bodies of Examples 21, 22, 25, 26, and 29 to 33 had sufficient shear strength.

When the bonding materials of Examples 3, 4, 7, 8, and 14 obtained by plating the surface of the sintered bodies were used, the shear strength of the obtained bonded bodies of Examples 23, 24, 27, 28, and 34 was sufficient.

When bonded bodies were obtained using the bonding materials of Examples 12 and 13 obtained by increasing the content of the solvent in the dispersion within the range of 5 mass% or more and 25 mass% or less, the shear strength of the bonded bodies of Examples 32 and 33 was sufficient.

The bonding materials of Comparative Examples 1 to 6 obtained using the dispersion containing only the silver particle group 1B had a porosity of less than 8% of the sintered body, and the shear strength of the bonding bodies of Comparative Examples 11 to 16 using these was not sufficient.

The bonding materials of Comparative Examples 7 to 10 using a dispersion having a solvent content of 26% had a sintered porosity greater than 30%, and the shear strength of the bonding bodies of Comparative Examples 17 to 20 using these bonding materials was not sufficient.

When the bonding materials of Comparative Examples 5, 6, 7, and 9 in which the surface of the sintered body was not polished and not plated were used, the shear strength of the obtained bonded bodies of Comparative Examples 25, 26, 27, and 29 was not sufficient.

In addition, as described below, the following was made clear by contrasting the bonding materials of Examples and the bonding materials of Comparative Examples under conditions (a) and (b).

<<Condition (a): Comparison of the composition of the silver powder in the dispersion and the same sintering conditions>>

(1) Contrast between the bonding material of Example 2 and the bonding material of Comparative Example 8

(2) Contrast between the bonding material of Example 6 and the bonding material of Comparative Example 10

(3) Contrast between the bonding material of Example 12 and the bonding material of Comparative Example 10

(4) Contrast between the bonding material of Example 13 and the bonding material of Comparative Example 10

Contrast between the bonding material of Example 2 and the bonding material of Comparative Example 8:

When manufacturing the bonding material, dispersion 1 for Example 2 and dispersion 8 for Comparative Example 8 were used, respectively, and the composition of the silver powder in the dispersion was silver particle group 1A/silver particle group 2A/silver Particle group 2B = 10/40/50 (% by mass).

As for the sintering conditions, the temperature and time during sintering were set to 250°C for 30 minutes, and the pressure during sintering was set to no pressure, and the surface of the sintered body was polished.

The surface roughness (μm) / porosity (%) / shear strength (MPa) of the bonded body in the bonding material were as follows.

2.79 μm / 10.6% / 22.3 MPa for Example 2 (Example 22)

For Comparative Example 8, 2.75 μm / 36.3% / 10.6 MPa (Comparative Example 18)

Contrast between the bonding material of Example 6 and the bonding material of Comparative Example 10:

When manufacturing the bonding material, dispersion 2 for Example 6 and dispersion 9 for Comparative Example 10 were used, respectively, and the composition of the silver powder in the dispersion was all silver particle group 1A/silver particle group 2A/silver Particle group 2B/silver particle group 3 = 5/20/25/50 (% by mass).

As for the sintering conditions, the temperature and time at the time of sintering were 250°C for 30 minutes, and the pressure at the time of sintering was not applied, and the surface of the sintered body was polished.

The surface roughness (μm) / porosity (%) / shear strength (MPa) of the bonded body in the bonding material were as follows.

2.36 μm / 13.1% / 22.1 MPa for Example 6 (Example 26)

For Comparative Example 10, 2.68 μm / 35.7% / 8.6 MPa (Comparative Example 20)

Contrast between the bonding material of Example 12 and the bonding material of Comparative Example 10:

When manufacturing the bonding material, dispersion 5 for Example 12 and dispersion 9 for Comparative Example 10 were used, respectively, and the composition of the silver powder in the dispersion was all silver particle group 1A/silver particle group 2A/silver Particle group 2B/silver particle group 3 = 5/20/25/50 (% by mass).

As for the sintering conditions, the temperature and time during sintering were set to 250°C for 30 minutes, and the pressure during sintering was set to no pressure, and the surface of the sintered body was polished.

The surface roughness (μm) / porosity (%) / shear strength (MPa) of the bonded body in the bonding material were as follows.

2.76 μm / 17.2% / 22.2 MPa for Example 12 (Example 32)

For Comparative Example 10, 2.68 μm / 35.7% / 8.6 MPa (Comparative Example 20)

Contrast between the bonding material of Example 13 and the bonding material of Comparative Example 10:

When manufacturing the bonding material, dispersion 6 for Example 13 and dispersion 9 for Comparative Example 10 were used, respectively, and the composition of the silver powder in the dispersion was all silver particle group 1A/silver particle group 2A/silver Particle group 2B/silver particle group 3 = 5/20/25/50 (% by mass).

As for the sintering conditions, the temperature and time during sintering were set to 250°C for 30 minutes, and the pressure during sintering was set to no pressure, and the surface of the sintered body was polished.

The surface roughness (μm) / porosity (%) / shear strength (MPa) of the bonded body in the bonding material were as follows.

2.61 μm / 26.3% / 21.7 MPa for Example 13 (Example 33)

For Comparative Example 10, 2.68 μm / 35.7% / 8.6 MPa (Comparative Example 20)

≪Condition (b): Comparison of bonding materials having the same surface roughness (1.06μm)≫

Contrast between the bonding material of Example 14 and the bonding material of Comparative Example 1:

The surface roughness (μm) / porosity (%) / shear strength (MPa) of the bonded body in the bonding material were as follows.

1.06 μm / 11.6% / 18.5 MPa for Example 14 (Example 34)

For Comparative Example 1, 1.06 μm / 5.3% / 12.5 MPa (Comparative Example 11)

From the comparison under the above condition (a) and condition (b), even if the surface roughness of the joint surface is about the same, the surface roughness is in a specific range (500 nm or more and 3.3 μm or less), and the porosity of the sintered body is a numerical value. It became clear that there is a significant difference in terms of the shear strength of the bonded body for each effect of the inside and outside of the limit (8 to 30%). In addition, with respect to the shear strength of the bonded body, it was also made clear that there was a significant effect throughout the numerical range (8 to 30%) of the porosity.

That is, when "porosity of the sintered body = 8 to 30%" and "surface roughness (Ra) of the joint surface = 500 nm or more and 3.3 μm or less" were combined, it became clear that the shear strength was particularly remarkable.

<Joint between silver-plated copper plate and conductor>

A conductor and a silver-plated copper plate are joined by heat treatment in the air using the bonding material of Example 1 at 200°C, 250°C, and 300°C at a pressure of 0.4 MPa or 1 MPa, respectively. Thus, a conjugate was obtained.

Fig. 3A is a microscopic image by SEM of a cross section of a bonded body obtained by bonding in the air by setting the pressure to 0.4 MPa and applying heat treatment at a temperature of 250°C. 3B is a graph showing the relationship between the shear strength of the bonded body and the temperature and pressure during sintering.

As a result, it was possible to bond the silver-plated copper plate and the conductor by applying the bonding material of Example 1 in the air. It became clear that the higher the temperature at the time of sintering and the higher the pressure at the time of sintering, the higher the shear strength.

<Joint between copper plate without plating and conductor>

Conductors and unplated copper plates (solid copper plates) were mixed with the bonding material of Example 14 in nitrogen at a pressure of 0.4 MPa or 1 MPa, and at temperatures of 250°C, 300°C, and 350°C. Bonding was performed by applying heat treatment at °C, respectively, to obtain a bonded body.

Fig. 4A is image pickup data by SEM of a cross section of a bonded body obtained by bonding in nitrogen by setting the pressure to 0.4 MPa and applying heat treatment at a temperature of 300°C. 4B is a graph showing the relationship between the shear strength of the bonded body and the temperature and pressure during sintering.

As a result, by applying the bonding material of Example 14 in nitrogen, it was possible to directly bond the unplated copper plate and the conductor. It became clear that the higher the temperature at the time of sintering and the higher the pressure at the time of sintering, the higher the shear strength.

According to the present invention, it is possible to provide a bonding material used for producing a bonded body having superior bonding strength than before, a manufacturing method of the bonding material, and a bonded body using the bonding material. The bonding material of the present invention can be used at high temperatures (eg, 300° C. or higher), which was difficult with conventional bonding materials, and is useful as a bonding material for electronic components including power semiconductors using silicon carbide (SiC). .

10... conjugate, 12 . . . conductor, 13 . . . bonding material, 14 . . . Board

Claims (7)

The silver powder includes a sintered body, and the porosity of the sintered body is 8 to 30%, as measured by the following [measurement of porosity of the sintered body],
A bonding material having a surface roughness (Ra) of the bonding surface of 1.06 µm or more and 3.3 µm or less.
[Measurement of Porosity of Sintered Body]
First, the sintered body is immersed in water, the volume of the sintered body is measured, and the mass of the sintered body is also measured. Further, the volume in case the sintered body corresponding to the mass does not have pores is calculated based on the theoretical density. The porosity of the sintered body is calculated from the measured volume and the theoretical volume in the case of not having pores. obtaining a sintered body by heating a coated film formed using a dispersion of a solvent and silver powder;
A step of coating the surface of the sintered body with at least one type of plating selected from the group consisting of silver, copper, tin, gold and nickel;
The method for producing a bonding material, wherein the content of the solvent in the dispersion is 5% by mass or more and 25% by mass or less. obtaining a sintered body by heating a coated film formed using a dispersion of a solvent and silver powder;
A step of coating the surface of the sintered body with at least one type of plating selected from the group consisting of silver, copper, tin, gold and nickel;
The silver powder includes a first silver particle group and a second silver particle group having different average particle diameters;
The average particle diameter of the first silver particle group is 50 nm or more and less than 1000 nm,
The method for producing a bonding material, wherein the average particle diameter of the second group of silver particles is 1 μm or more and less than 20 μm. The method of claim 3,
The method for producing a bonding material, wherein the silver powder further includes a third group of silver particles having an average particle diameter of 20 μm or more and less than 60 μm. The method according to any one of claims 2 to 4,
In the step of obtaining the sintered body, the coating film is heated while the pressure applied to the coating film is 5 MPa or less. A bonded body in which a conductor and a substrate are bonded by the bonding material according to claim 1. delete

Images